﻿
<!DOCTYPE html>

<html>
<head>
    <meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
    <title>06_键盘输入和纹理过滤</title>

    <script type="text/javascript" src="../js/Oak3D_v_0_5.js"></script>

    <script id="shader-fs" type="x-shader/x-fragment">

        precision mediump float;


        varying vec2 vTextureCoord;

        uniform sampler2D uSampler;

        void main(void) {
        gl_FragColor = texture2D(uSampler, vec2(vTextureCoord.s, vTextureCoord.t));
        }
    </script>

    <script id="shader-vs" type="x-shader/x-vertex">
        attribute vec3 aVertexPosition;
        attribute vec2 aTextureCoord;

        uniform mat4 uMVMatrix;
        uniform mat4 uPMatrix;

        varying vec2 vTextureCoord;


        void main(void) {
        gl_Position = uPMatrix * uMVMatrix * vec4(aVertexPosition, 1.0);
        vTextureCoord = aTextureCoord;
        }
    </script>


    <script type="text/javascript">

        var gl;

        function initGL(canvas) {
            try {
                gl = canvas.getContext("experimental-webgl");
                gl.viewportWidth = canvas.width;
                gl.viewportHeight = canvas.height;
            } catch (e) {
            }
            if (!gl) {
                alert("Could not initialise WebGL, sorry :-(");
            }
        }


        function getShader(gl, id) {
            var shaderScript = document.getElementById(id);
            if (!shaderScript) {
                return null;
            }

            var str = "";
            var k = shaderScript.firstChild;
            while (k) {
                if (k.nodeType == 3) {
                    str += k.textContent;
                }
                k = k.nextSibling;
            }

            var shader;
            if (shaderScript.type == "x-shader/x-fragment") {
                shader = gl.createShader(gl.FRAGMENT_SHADER);
            } else if (shaderScript.type == "x-shader/x-vertex") {
                shader = gl.createShader(gl.VERTEX_SHADER);
            } else {
                return null;
            }

            gl.shaderSource(shader, str);
            gl.compileShader(shader);

            if (!gl.getShaderParameter(shader, gl.COMPILE_STATUS)) {
                alert(gl.getShaderInfoLog(shader));
                return null;
            }

            return shader;
        }


        var shaderProgram;

        function initShaders() {
            var fragmentShader = getShader(gl, "shader-fs");
            var vertexShader = getShader(gl, "shader-vs");

            shaderProgram = gl.createProgram();
            gl.attachShader(shaderProgram, vertexShader);
            gl.attachShader(shaderProgram, fragmentShader);
            gl.linkProgram(shaderProgram);

            if (!gl.getProgramParameter(shaderProgram, gl.LINK_STATUS)) {
                alert("Could not initialise shaders");
            }

            gl.useProgram(shaderProgram);

            shaderProgram.vertexPositionAttribute = gl.getAttribLocation(shaderProgram, "aVertexPosition");
            gl.enableVertexAttribArray(shaderProgram.vertexPositionAttribute);

            shaderProgram.textureCoordAttribute = gl.getAttribLocation(shaderProgram, "aTextureCoord");
            gl.enableVertexAttribArray(shaderProgram.textureCoordAttribute);

            shaderProgram.pMatrixUniform = gl.getUniformLocation(shaderProgram, "uPMatrix");
            shaderProgram.mvMatrixUniform = gl.getUniformLocation(shaderProgram, "uMVMatrix");
            shaderProgram.samplerUniform = gl.getUniformLocation(shaderProgram, "uSampler");
        }


        function handleLoadedTexture(textures) {
            gl.pixelStorei(gl.UNPACK_FLIP_Y_WEBGL, true);

            gl.bindTexture(gl.TEXTURE_2D, textures[0]);
            gl.texImage2D(gl.TEXTURE_2D, 0, gl.RGBA, gl.RGBA, gl.UNSIGNED_BYTE, textures[0].image);
            gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_MAG_FILTER, gl.NEAREST);
            gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_MIN_FILTER, gl.NEAREST);

            gl.bindTexture(gl.TEXTURE_2D, textures[1]);
            gl.texImage2D(gl.TEXTURE_2D, 0, gl.RGBA, gl.RGBA, gl.UNSIGNED_BYTE, textures[1].image);
            gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_MAG_FILTER, gl.LINEAR);
            gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_MIN_FILTER, gl.LINEAR);

            gl.bindTexture(gl.TEXTURE_2D, textures[2]);
            gl.texImage2D(gl.TEXTURE_2D, 0, gl.RGBA, gl.RGBA, gl.UNSIGNED_BYTE, textures[2].image);
            gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_MAG_FILTER, gl.LINEAR);
            gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_MIN_FILTER, gl.LINEAR_MIPMAP_NEAREST);
            gl.generateMipmap(gl.TEXTURE_2D);

            gl.bindTexture(gl.TEXTURE_2D, null);
        }


        var crateTextures = Array();

        function initTexture() {
            var crateImage = new Image();

            for (var i = 0; i < 3; i++) {
                var texture = gl.createTexture();
                texture.image = crateImage;
                crateTextures.push(texture);
            }

            crateImage.onload = function () {
                handleLoadedTexture(crateTextures)
            }
            crateImage.src = "../texture/crate.gif";
        }


        var mvMatrix;
        var mvMatrixStack = [];
        var pMatrix;


        function mvPushMatrix() {
            var copy = new okMat4();
            mvMatrix.clone(copy);
            mvMatrixStack.push(copy);
        }

        function mvPopMatrix() {
            if (mvMatrixStack.length == 0) {
                throw "Invalid popMatrix!";
            }
            mvMatrix = mvMatrixStack.pop();
        }


        function setMatrixUniforms() {
            gl.uniformMatrix4fv(shaderProgram.pMatrixUniform, false, pMatrix.toArray());
            gl.uniformMatrix4fv(shaderProgram.mvMatrixUniform, false, mvMatrix.toArray());
        }

        var xRot = 0;
        var xSpeed = 0;

        var yRot = 0;
        var ySpeed = 0;

        var z = -5.0;

        var filter = 0;


        var currentlyPressedKeys = {};

        function handleKeyDown(event) {
            currentlyPressedKeys[event.keyCode] = true;

            if (String.fromCharCode(event.keyCode) == "F") {
                filter += 1;
                if (filter == 3) {
                    filter = 0;
                }
            }
        }


        function handleKeyUp(event) {
            currentlyPressedKeys[event.keyCode] = false;
        }


        function handleKeys() {
            if (currentlyPressedKeys[33]) {
                // Page Up
                z -= 0.05;
            }
            if (currentlyPressedKeys[34]) {
                // Page Down
                z += 0.05;
            }
            if (currentlyPressedKeys[37]) {
                // Left cursor key
                ySpeed -= 1;
            }
            if (currentlyPressedKeys[39]) {
                // Right cursor key
                ySpeed += 1;
            }
            if (currentlyPressedKeys[38]) {
                // Up cursor key
                xSpeed -= 1;
            }
            if (currentlyPressedKeys[40]) {
                // Down cursor key
                xSpeed += 1;
            }
        }


        var cubeVertexPositionBuffer;
        var cubeVertexTextureCoordBuffer;
        var cubeVertexIndexBuffer;
        function initBuffers() {
            cubeVertexPositionBuffer = gl.createBuffer();
            gl.bindBuffer(gl.ARRAY_BUFFER, cubeVertexPositionBuffer);
            vertices = [
                // Front face
                -1.0, -1.0, 1.0,
                 1.0, -1.0, 1.0,
                 1.0, 1.0, 1.0,
                -1.0, 1.0, 1.0,

                // Back face
                -1.0, -1.0, -1.0,
                -1.0, 1.0, -1.0,
                 1.0, 1.0, -1.0,
                 1.0, -1.0, -1.0,

                // Top face
                -1.0, 1.0, -1.0,
                -1.0, 1.0, 1.0,
                 1.0, 1.0, 1.0,
                 1.0, 1.0, -1.0,

                // Bottom face
                -1.0, -1.0, -1.0,
                 1.0, -1.0, -1.0,
                 1.0, -1.0, 1.0,
                -1.0, -1.0, 1.0,

                // Right face
                 1.0, -1.0, -1.0,
                 1.0, 1.0, -1.0,
                 1.0, 1.0, 1.0,
                 1.0, -1.0, 1.0,

                // Left face
                -1.0, -1.0, -1.0,
                -1.0, -1.0, 1.0,
                -1.0, 1.0, 1.0,
                -1.0, 1.0, -1.0,
            ];
            gl.bufferData(gl.ARRAY_BUFFER, new Float32Array(vertices), gl.STATIC_DRAW);
            cubeVertexPositionBuffer.itemSize = 3;
            cubeVertexPositionBuffer.numItems = 24;

            cubeVertexTextureCoordBuffer = gl.createBuffer();
            gl.bindBuffer(gl.ARRAY_BUFFER, cubeVertexTextureCoordBuffer);
            var textureCoords = [
                // Front face
                0.0, 0.0,
                1.0, 0.0,
                1.0, 1.0,
                0.0, 1.0,

                // Back face
                1.0, 0.0,
                1.0, 1.0,
                0.0, 1.0,
                0.0, 0.0,

                // Top face
                0.0, 1.0,
                0.0, 0.0,
                1.0, 0.0,
                1.0, 1.0,

                // Bottom face
                1.0, 1.0,
                0.0, 1.0,
                0.0, 0.0,
                1.0, 0.0,

                // Right face
                1.0, 0.0,
                1.0, 1.0,
                0.0, 1.0,
                0.0, 0.0,

                // Left face
                0.0, 0.0,
                1.0, 0.0,
                1.0, 1.0,
                0.0, 1.0,
            ];
            gl.bufferData(gl.ARRAY_BUFFER, new Float32Array(textureCoords), gl.STATIC_DRAW);
            cubeVertexTextureCoordBuffer.itemSize = 2;
            cubeVertexTextureCoordBuffer.numItems = 24;

            cubeVertexIndexBuffer = gl.createBuffer();
            gl.bindBuffer(gl.ELEMENT_ARRAY_BUFFER, cubeVertexIndexBuffer);
            var cubeVertexIndices = [
                0, 1, 2, 0, 2, 3,    // Front face
                4, 5, 6, 4, 6, 7,    // Back face
                8, 9, 10, 8, 10, 11,  // Top face
                12, 13, 14, 12, 14, 15, // Bottom face
                16, 17, 18, 16, 18, 19, // Right face
                20, 21, 22, 20, 22, 23  // Left face
            ]
            gl.bufferData(gl.ELEMENT_ARRAY_BUFFER, new Uint16Array(cubeVertexIndices), gl.STATIC_DRAW);
            cubeVertexIndexBuffer.itemSize = 1;
            cubeVertexIndexBuffer.numItems = 36;
        }


        function drawScene() {
            gl.viewport(0, 0, gl.viewportWidth, gl.viewportHeight);
            gl.clear(gl.COLOR_BUFFER_BIT | gl.DEPTH_BUFFER_BIT);

            pMatrix = okMat4Proj(45, gl.viewportWidth / gl.viewportHeight, 0.1, 100.0);

            mvMatrix = okMat4Trans(0.0, 0.0, z);

            mvMatrix.rotX(OAK.SPACE_LOCAL, xRot, true);
            mvMatrix.rotY(OAK.SPACE_LOCAL, yRot, true);


            gl.bindBuffer(gl.ARRAY_BUFFER, cubeVertexPositionBuffer);
            gl.vertexAttribPointer(shaderProgram.vertexPositionAttribute, cubeVertexPositionBuffer.itemSize, gl.FLOAT, false, 0, 0);

            gl.bindBuffer(gl.ARRAY_BUFFER, cubeVertexTextureCoordBuffer);
            gl.vertexAttribPointer(shaderProgram.textureCoordAttribute, cubeVertexTextureCoordBuffer.itemSize, gl.FLOAT, false, 0, 0);


            gl.activeTexture(gl.TEXTURE0);
            gl.bindTexture(gl.TEXTURE_2D, crateTextures[filter]);
            gl.uniform1i(shaderProgram.samplerUniform, 0);

            gl.bindBuffer(gl.ELEMENT_ARRAY_BUFFER, cubeVertexIndexBuffer);
            setMatrixUniforms();
            gl.drawElements(gl.TRIANGLES, cubeVertexIndexBuffer.numItems, gl.UNSIGNED_SHORT, 0);
        }


        var lastTime = 0;

        function animate() {
            var timeNow = new Date().getTime();
            if (lastTime != 0) {
                var elapsed = timeNow - lastTime;

                xRot += (xSpeed * elapsed) / 1000.0;
                yRot += (ySpeed * elapsed) / 1000.0;
            }
            lastTime = timeNow;
        }


        function tick() {
            okRequestAnimationFrame(tick);
            handleKeys();
            drawScene();
            animate();
        }



        function webGLStart() {
            var canvas = document.getElementById("lesson06-canvas");
            initGL(canvas);
            initShaders();
            initBuffers();
            initTexture();

            gl.clearColor(0.0, 0.0, 0.0, 1.0);
            gl.enable(gl.DEPTH_TEST);

            document.onkeydown = handleKeyDown;
            document.onkeyup = handleKeyUp;

            tick();
        }

    </script>


</head>


<body onload="webGLStart();">
    <canvas id="lesson06-canvas" style="border: none;" width="500" height="500"></canvas>

    <h2>键盘控制说明：</h2>

    <ul>
        <li>使用<code>Page Up</code>键和<code>Page Down</code>键来进行缩放。
        <li>使用方向键来旋转（你按住方向键时间越长，旋转的越快）。
        <li>使用<code>F</code> 键来切换三种不同的纹理过滤。
    </ul>
</body>

</html>